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1968 Ballast Resistor

BigJim

Well-known member
Joined
Feb 2, 2012
Messages
414
The ballast resistor in the 68 CS needs replacement. I looked on Summit's site and it appears I need the ohm rating of the resistor since theirs are all generic application listed by ohms. I checked CJP and they only sold one as part of a MSD coil package. The closest thing thing I could find on NPD is some kind of wire. The car has the white .5 x .5 x 3 inch block on the inner wheel well which I'm sure is a resistor. Does anyone know the ohms or better yet a part number?

Thanks
 

Mosesatm

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Joined
Jan 18, 2005
Messages
9,009
Please don't take my word for this but I'm pretty sure you shouldn't have a resistor. The pink wire coming out of the switch is a resistor wire so adding a ballast resistor is too much.
 

franklinair

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Joined
Mar 1, 2007
Messages
4,740
I am not aware of any 'dropping' resistor on '68 Mustangs other than the blower motor speed control.
Where do the wires go to/from the resistor in your Mustang?

Neil
 

rvrtrash

Well-known member
Joined
Apr 25, 2003
Messages
3,649
Fords of that era didn't use external ballast resistors. Dodge liked using the external resistor in their ignitions. Arlie is correct that the wire to the coil is a resistance wire, and serves the same purpose. The wire from NPD is probably a replacement if yours is cut or damaged. I can't measure the input resistance of a coil right now, because my meter is at work, but I believe it's about 1.5 - 2.0 ohms, and the coil normally runs at about 8 volts (all going off memory and subject to failure). As such your external resistor is probably about 1 ohms and rated for around 10 amps, if you want to just replace what you have. Again, I can't be positive because it's been a long time since I looked at this, and can't verify right now.

Steve
 
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BigJim

BigJim

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Joined
Feb 2, 2012
Messages
414
The car had an external ballast resister mounted to the fender when I got it. It also had a home made wiring harness under the dash. So my guess is at some point the PO replaced the wiring harness and the resister wire. FWIW the PO had bypassed the factory fog light switch with a Radio Shack toggle switch. Basically the wiring was a mess.
 
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BigJim

BigJim

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Joined
Feb 2, 2012
Messages
414
Got all new harnesses on order from CJ's. Should have them Tuesday or Wednesday. Hopefully she'll be running next weekend without a ballast resistor.

Sent from my SM-G920P using Tapatalk
 

robert campbell

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Joined
Apr 10, 2007
Messages
4,321
Be ready for lots of work! Replacing all the wiring is a time consuming and difficult job. Hope you have both bucket seats out and are ready for lots of fun under the dash!!

I hate working under the dash!! Just did a project on my brothers 67 Fastback with a console...... I need a nice young person to do this type of work!

Rob
 
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BigJim

BigJim

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Joined
Feb 2, 2012
Messages
414
Not only are the seats out but the entire interior is out including the dash which is completely torn apart.

Sent from my SM-G920P using Tapatalk
 

franklinair

Well-known member
Joined
Mar 1, 2007
Messages
4,740
Are you running a stock ignition system or an after market (Pertronix, etc.) system?
IIRC the stock system puts 12V to the coil in the START position, then 8V in the RUN position (through the Pink resistance wire).

I use Pertronix II installation on my cars (with the Pertronix 40,000 volt coil) which uses 12V in both the START & RUN position, bypassing the Pink resistance wire.

Neil
 
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